Rock drill of the valveless type



March 15, 1932. A G. SLATCHER V 1,849,208

' ROCK DRILL OF THE VALVELESS TYPE Filed Feb. 25, 1928 Patented Mar. 15, 1 932 7 ALFRED G.. snAi'cHER, Ont-CLEVELAND, onto; a smmn to THE CLEVELAND iaoex 1 1 .:onILLicoMPANYmFcLEvELANn'oHIo r 1 Roo ame Eran 'VALVELESS TYPE .a plicatioh' fiieart iia yzs, '1e3 ser'ial mama.

The present inventionis v directed to improvementszin rock drills off-the valveless' I The-chamber through. the 'exhaust port 16. The-piston: I hammer is formed witha head 17pfo'r type; P Y

The primary 5 provide ,a' device of this charactenso cone structed that the piston hammer during its movement controls the admittance of the motive fluid to and from the hammer without: the use of complicated valve mechanisms.

Another object of the invention is to simplify the construction of drills of this type, the construction being such that the piston ham mer will be rapid and positive in its operav tion.

' bers 2 and 3, respectively,

head and block.

can be manufactured at a relatively small With these and other objects in view, this invention resides in the novel features of construction, formation, combination and ar rangement of parts to be hereinafter more, fully described, claimed and illustrated in the accompanying drawings, in which:

Figure 1 is a longitudinal sectional view. 7 Figure 2 is a sectional view taken transversely through the exhaust port. I

Referring to the drawings, ldesignates the cylinder having front and rear pistonjchamthe diameter of the formerbeing greater than the latter to accommodate the difi'erential piston V hammer 4. The rear piston chamber is formed in the cylinder block 5 and sleeve 6 which fits between theback head 7 and said block, said sleeve defining an annular chamber 8 between the back The block has a passage 9 formed longitudinally therein which aflords communication between the relatively large,

constant pressure chamber 10 formed between 1 the chambers 2 and 3.

The forward end of the chamber 2 isc'losed by the tappet case 11, which as usual, is interposed between the front head 12 and cylinder 1, therebeing a tappet 13 shown in the case for striking the drill steel 14 V The chambers 2 and 3 are connected by a motive fluid passage 15 which has its ends object of the invention is to jopen; the outer ends dinal bore 21 in the end "of said bore opening into'the chamberv 3, whilethe forward endthereof stopsat apoint slightly"beyondtheinne r ends ofrthe ports a cost, and one which is durable and elficient in 20' I I i i operation.

Another object ofthe invention is to pro vide a (hill of this kind so constructed that it j VVhen in this posit tive chambers.

movement in the: chamber 2 and chamber 10, and, "further includes a with an annular exte ior groove 19 in which opening into the forwardfends of the'respec- '2 a "open to atmosphere "d'uced" neCkTlS-CK The'lhead isprovided "do i of the radially-disposed ports20, saidports havingftheir'inner ends opening into the forwarden'd of theil'ongitu piston hammer, the rear The back head has carriedtherebya'spring controlled live air controlling valve 22 mount,

Port 24; The valve 22 s p upon actuat' Q ing' thelever 25 v o u o mountefdsron the r handle 26 carried y e back head, as is customary. i s i z As "shown in Figure 1, thepiston hammer 1s m position to-begin lts rearward 'stroke.

gPressur'e fiuidlpasses'from the chamber .8,

through passage 9f'andfinto the pressure chamber 1'0,thepressure-remaining constant as long as the-valve 22 is open.- As the pis ton hammer moves rearwardly the groove 18 18 so located as to permit pressure fluid to passthrough the passage 15 to act upon'the front faceof the piston hammer,--thus driving the same rearwardly; to its fullest 'exte'nt.

11 and just before ithe "ed in 'a'chambe'r 23', thechamber being com- *munication with the chamber- 8 through a piston hammerstarts'onfits forward stroke the .po'rts 20 open into 'the"chamber10.y It

ward stroke the groove 19 is positioned in the chamber 10 so that pressure fluidsfrom said chamber will enter the ports, 20' and to will be of course understood that just beforea the piston hammer bore 21, thus acting upon-the rear end of v the 'pistonlto drive the same forwardly, Without resistance since there is no pressure upon the front face of the piston due to the presence of the exhaust port 16.

What is claimed is 1. In a tool of the class described, the combination with a cylinder having large and small chambers, and a relatively large constant pressure air chamber therebetween, said cylinder having an exhaust port opening into i the large chamber, a piston hammer includ ing a head and stem movable, respectively, in the large and small chambers, a reduced neck formed on the stem, said cylinder hav' ing a motive fluid conducting passage connecting the forward ends of the respective chambers, said stem and neck serving to alternately cut off and permit passage of motiye fluid through the passageway to the large chamber, means controlled by the stem for conducting motive fluidfrom the constant air chamber to the rear-end of thestem, said head being subjected constantly to theipresy sure of the air in the constant air chamber; I

communicating with said chambers, a piston hammer including a head and a stem movable respectively in said chambers, there being a fluid conducting passage in said cylinder communicating with the front ends of said chambers, said piston hammer having an axial bore therein adapted to intermittently communicate with said pressure chamber to permit fluid to pass to the rear end of the hammer to act on the stem, there being an exhaust port communicating with the atmosphere from the forward chamber,

saidbore in 'the'ha-mmer intermittently communicating with said exhaust port when moved out of communicatlon with the pressure chamber, and means. carried by sald stem for controlling the flow of pressure fluid to the front end of the forward chamber through said passage.

In testimony whereof I affixmysignature a ALFRED G. SLAT-CHER.v

2. In a tool ofthe class described, the com- Ybinatidnwith a cylinder having large'and small chambers, of a piston ,1n the cylinder and including a head and hammer movable stem movable, respectively, in the large and small chambers, said cylinder having a con stant air chamber between the large and small chambers, a motive fluid passageway connecting the :front ends of the respective chambers, a reduced neck formed in the stem, said stem and head having a bore formed therein for conducting motive fluid from the constant air chamber to the rearend of the small chamber when the piston hammer is in one position, said neck permitting motive fluid from the constant air chamber to "pass to the front end of the large chamber for action against said head, when in another position, and means for exhausting fluid from thebore.

3. In a tool of the class described, a cylinder having large and small chambers, a rela- 5 tively large constant air pressure chamber therebetween, a piston hammer including a head and stem movable, respectively, in the said chambers, said cylinder having a motive fluid conducting passage connecting the front ends of the respective chambers, .said piston hammer having a bore therein, and ports at one end opening into the pressure chamber intermittently to permit pressure fluid to pass to act upon the stem, the cylinder having'an exhaust port leading from the large chamher, the ports of the hammer discharging through the exhaust port when moved from to the rear end of the hammer the pressure chamber, and means carried by the stem for controlling the flow of pressure fluid through the passage to the front end of the large chamber.

4. In a tool of theclass described, a cylinder having a pair of chambers therein, a relatively large constant air pressure chamber 

